I ICMIEE18-326CMIEE18-326 Cleaning of Accumulated Dust

International Conference on Mechanical, Industrial and Energy Engineering 2018

23-24 December, 2018, Khulna, BANGLADESH

* Corresponding author. Tel.: +88-01784353193

E-mail addresses: [email protected]

I ICMIEE18-326CMIEE18-326

Cleaning of Accumulated Dust Particle of a Flat Plate Solar Collector

Amir Hamza Limon, Muhammad Mostafa Kamal Bhuiya*, Mostafizur Rahman and Majedul Islam

Department of Mechanical Engineering, Chittagong University of Engineering & Technology (CUET), Chittagong 4349,

BANGLADESH

ABSTRACT

An experimental investigation was carried out to find out the effective cleaning method of the glazing material of solar

collector. The study emphasized on solar panel glazing material cleaning process using water force impinging by a nozzle.

A nozzle is used to make a water jet having a velocity which is impacted on the glazing material of a solar plate collector.

The project investigated the optimum position of nozzle with respect to glass at which the dust removing rate is maximum.

The jet of different velocities were used to perform the experiment and the maximum tangential force was found between

30º-40º relative angle of impacted jet with respect to the glazing material at which the maximum cleaning can be possible.

This project will help to ensure the maximum amount of solar beam reach to the receiver for power generation. It can be

noted that this technique will help to clean the solar collector with a reasonable cost and effectively.

Keywords: Accumulated dust, Cleaning, Water force, Nozzle, Glazing material

1. Introduction

Globally, we are bound in different types of energy

sources. But, in the past several decades energy

requirements have been increased significantly and

predicted that it rises to 50% by 2030(world energy

outlook,2011). At this time, these requirements are met

mostly from the conventional way (like coal, gas, oil

etc.). Environment is being polluted by their exhaust

and their reserves will be nearly finished after some era.

For this reasons, implementation of renewable energy

sources like solar power are rising. After

implementation of solar panels some difficulties arise of

their performance. Dust accumulation over glass plate

of solar panels is one of the biggest problems because

dust obscures the solar radiation and therefor reduces

their efficiency, especially in those countries whose

environmental condition is hard. Dust accumulation

mostly depends on weather condition and geographical

locations. To reduce this loss, many researchers have

been developed different types of solar collector

cleaning techniques and many of them are researching.

The categories of cleaning solutions considered in this

study include the following: manual cleaning,

mechanized cleaning, hydraulic cleaning, installed

robotic cleaning and deployable robotic cleaning [1].

Removal of dust particles from the surface of the solar

cells and solar collectors is performed using surfactants

[2]. A shield contains a clear panel with embedded

parallel electrodes connected to a single-phase AC

supply for producing an electromagnetic wave. The

electromagnetic field produced by the electrodes on the

surface of the panel repels dust particles that have

already deposited on the panel surface, and prevents the

deposition of further particles if they are charged with

positive or negative polarities [3]. A deep study about

the effectiveness of different cleaning methods,

including natural cleaning, has been performed during

two years in a semi-desert climate. Different cleaning

methods were periodically applied to several reflector

samples exposed in four separated test benches.

Monochromatic specular reflectance measurements

were taken before and after applying the cleaning

methods [4]. The self-cleaning technology for solar cell

array can promote efficiency of electricity produced and

protect the solar cell. The methods of dust-removal,

such as natural means, mechanical means, self-cleaning

nano-film, and electrostatic means are presented [5].

The influence of cleaning on the PV panels using water

as well as a surfactant was investigated experimentally

using a non-pressurized water system [6]. Dust problem

and recent developments made on automated cleaning

system for solar photovoltaic modules which give brief

overview on techniques like electrical, mechanical,

chemical and electro static [7]. Fabricated

superhydrophobic microshell PDMS showed a superior

dust cleaning effect compared to that of flat PDMS,

preventing the degradation by dust particles of solar cell

efficiency. This transparent, flexible and

superhydrophobic microshell PDMS surface provides

feasibility for a practical application of

superhydrophobic surfaces in solar cells [8]. A self-

cleaning effect developed through the use of a super

hydrophobic and water-repellent surface was

demonstrated for solar cell applications [9]. A perfectly

ordered microshell array was fabricated on a transparent

and flexible polydimethylsiloxane (PDMS) elastomer

surface. self-cleaning solar panels may be manufactured

incorporating electrodynamic screens that will derive

their power from the panel itself about 10 watts per

square meter of a solar panel. This power is a small

fraction of the power generated by a typical panel (800

watts) and is used only when cleaning is needed [10].

Many efforts have been made to address the severity of

deposited particles like dust, water stains, carbon from

smoke, pollen in agricultural regions, etc. on the

efficiency reduction of solar devices, which results in

additional costs either from oversizing the system or

from cleaning it [11]. In the current study, the

experimental data concerning the effect of three

representative air pollutants (i.e., red soil, limestone and

ICMIEE18-326- 2

carbonaceous fly-ash particles) on the energy

performance of PV installations are analyzed.

According to the results obtained, a considerable

reduction of PVs’ energy performance is recorded,

depending strongly on particles’ composition and

source[12]. Effect of dust, humidity and air velocity

influences of the efficiency of photovoltaic cells[13].

Most popular solar collector concentrating technologies

are Flat plate solar collector. In this paper, force of

hydraulic jet impinging from nozzle is used for cleaning

Flat solar panel collector and find out a better relative

angle between plate & flow for better performance. All

the tangential force acting on the plate can remove the

dust, but highest force can remove maximum dust from

the collector in minimum time. It can be seen that the dust accumulation over solar

collector is one of the biggest problems because dust

obscures the solar radiation and therefore, reduces their

efficiency. However, minimizing the cost of the

cleanliness is a key issue for the solar-plant feasibility.

Therefore, this work focused on optimizing the cleaning

method of solar reflectors for CSP applications under

real outdoor conditions in a semi-desert or hard climate.

2. Experimental Procedure

The study relates to cleaning glazing material of solar

collector or other glass plates by using water jet

impinging from nozzle, particularly for cleaning

surfaces which may be horizontal, vertical or any other

angular position. When a water jet strikes a plate with a

force it flashes the surface. This force divided by normal

force which acts normally to the plate and tangential

force which act tangent of the surface. Normal force is

responsible for wearing the surface and produces

separation in water after striking. Water with tangential

force move along the surface and washed away the dust

particles along its path. If the tangential force increases

water can washed away maximum possible of different

type dust (oily dust, heavy particulates, Electrostatic

precipitators etc.). As well as amount of water and time

needed for proper cleaning reduces with increasing the

tangential force of water jet. So, it is important to know

better position of nozzle relative to the glazing plate

from where jet is impinged.

Labor costs, maintenance cost and other technical cost

could be lower by using this technique compare to other

technique stated at previous article. This technique is

convenient for those area where availability of water

source is found lower as minimum amount of water

needed for proper cleaning when the better position of

nozzle is found.

2.1 Experimental setup

To conduct the experiment to find out better relative

position of nozzle with respect to the glazing material

several equipment were used. The experiment was

conducted at Chittagong University of Engineering and

Technology. Glass plate is a plate or may be a collector

solar panel over which water jet is impacted at different

height or angular position. It is placed on a force

measuring device which calculates normal force of the

impacted jet. It is connected to another force measuring

device with wire which calculates tangential force.

Wooden frame is a frame made of wood or ply which

carries all other components. Two wooden frames were

used, one was vertical, and one was horizontal. One

weight measuring device measures normal force of

impacted jet and another weight measuring device

measures tangential force of impacted jet. Different

sizes of pipes are used. One main pipe carried water

with a nozzle connected to its middle from which water

jet is released, constructed such a manner that it can

rotate with a fixed height at different angle and can slide

on a vertical scale at a fixed angle. A nozzle is

structured at the middle of the main pipe such a manner

that water jet released through it can splash maximum

area of the glass plate. Pipe fittings are used to connect

different pipe section where necessary. Rollers are used

to minimize friction between the glazing material and

the weight measuring scale.

In this experiment all the equipment is assembled to

accomplish desired setup for finding out dependent

variable or tangential force by manipulating the

independent variable or relative angle of nozzle and

glass plate.

Fig. 1 (a) Glass plate; (b) Weight measuring scale; (c)

PVC pipes; (d) Pipe fittings; e) Roller.

2.2 Experimental procedure

At first, horizontal wooden frame is made for the

mechanical support which protects the other equipment.

A vertical frame with a groove in the middle is made

which can roll in horizontal direction along the

horizontal wood frame. A 2-inch diameter PVC pipe is

made in such a way that it’s one end is closed with

suitable fittings and other end is connected to a smaller

0.5inch diameter pipe with a bell reducer and nipple

fittings. This smaller pipe is connected to the water

source. A 3.5mm diameter nozzle relates to a tee fitting

at the middle of that pipe.

(a)

(c)

(b)

(e)

(d)

ICMIEE18-326- 3

Fig.2 A cleaning method of a glass plate as a glazing

material

The whole pipe with the nozzle can made an up and

down movement along the groove of the vertical frame.

A vertical scale or ruler is placed vertically along

vertical frame which indicate the vertical position (h) of

the pipe or nozzle position with respect to glass plate.

An angular scale is positioned at the closed end of the

PVC pipe which indicates the angular position of the

nozzle with respect to flat glass plate.

Fig. 3 (a) Weight measuring device with glass plate and

roller; (b) Angular and vertical position measurement

The PVC pipe with nozzle can move up and down by

lifting it by rope system. A weight measuring device is

placed horizontally on the horizontal wooden frame just

below the main pipe. This device can measure the

normal force of the impacted jet striking on the glass

plate. It can be calibrated. A glass plate is placed over

the weight measuring device over which water jet is

impacted. Between the glass plate and weight measuring

device 4 roller are placed such a way that glass plate is

situated over these rollers. The main tasks of these

rollers are to minimize the friction between weight

measuring device and glass plate. The water jet is

impacted on the flat glass plate with a particular striking

force and a particular relative angle between glass plate

and impinging water jet. A normal force is measured by

the weight measuring device. With the angle and this

normal force, we can easily find out the striking force of

the jet and tangential force. Our main aim is to find out

the angle at which tangential force is maximum. This

system includes cleaning using a fixed nozzle or a

sliding nozzle from which water exits at high speed,

located at the top of the panel. Water is pumped by a

pump through pipe to the nozzle. A water jet is released

from the nozzle which is impacted on the collector with

a force controlled by operator. The point of impact of

water jet on the collector can be changed by operator

through controlling the angle between jet and plate.

Tangential and normal component of impacted force

can be measured from force or weight measuring device.

3. Results and discussion

In the experiment normal forces are collected at

different heights and different angles simultaneously as

shown in Fig.4. At first a relative height of the main

pipe from where the nozzle is connected to the

horizontal glass plate is fixed. Then different normal

forces (kg) are collected with 10º interval from 90º to

10º or 20º. Then another relative height is fixed, and

normal force is collected. The height changes with 2.54

cm interval from 12 cm to 24.7 cm.

When the jet velocity is 7.2236 m/s:

Different force acting on the glass plate which are

changed by changing relative angular direction of water

jet and by changing height. First fixed the height and

angle of jet is manipulated to find out different value of

the forces.

Fig. 4 Force analysis

Fn = Normal force;

Ft = Tangential force;

F = Jet striking force;

In this experiment we manipulated angle, α and found

normal force Fn. Jet striking force F and tangential force

Ft can be found by,

When height of the main pipe or nozzle from the glass

plate is 12cm reducing as shown in Fig.5 (a) the relative

angle brought the normal force and jet striking force

(a) (b)

ICMIEE18-326- 4

into a decreasing line and at the same time tangential

force is increasing. Maximum tangential force is found

at 10º which is 2. 423N. When height of the main pipe

or nozzle from the glass plate is 14.54cm as shown in

Fig.5(b) reducing the relative angle brought the normal

force and jet striking force into a decreasing line and at

the same time tangential force is increasing. Maximum

tangential force is found at 30º which is 2.1036N. When

height of the main pipe or nozzle from the glass plate

is17.08 cm as shown in Fig.5(c) maximum tangential

force is found at 10º which is 2.224N. When height of

the main pipe or nozzle from the glass plate is 19.62 cm

as shown in Fig.5(d) maximum tangential force is found

at 40º which is 2.2323N. When height of the main pipe

or nozzle from the glass plate is 22.16cm as shown in

Fig.5(e) maximum tangential force is found at 40º

which is 2.4538N. When height of the main pipe or

nozzle from the glass plate is 24.7cm as shown in

Fig.5(f) maximum tangential force is found at 30º which

is 2.5987N.

Fig. 5 Relative angle vs. different forces acting on the

plate h=12 cm (a); h=14.54 cm (b); h=17.08 cm (c);

h=19.62 cm (d); h =22.16 cm (e); h=24.7 cm (f); and

velocity of jet is 7.2236 m/s.

When height of the main pipe or nozzle from the glass

plate is 22.16 cm as shown in Fig.7(e) maximum

tangential force is found at 30º which is 3.0578N. When

height of the main pipe or nozzle from the glass plate is

24.7cm as shown in Fig.7(f) maximum tangential force

is found at 30º which is 3.2273N.


plate when; h=12 cm (a); h=14.54 cm (b); h=17.08 cm

(c); h=19.62 cm (d); h=22.16 cm (e); h=24.7 cm (f) and



First fixed the height and angle of jet is manipulated to

find out different value of the forces. When height of

the main pipe or nozzle from the glass plate is 12cm as

shown in Fig.6(a) maximum tangential force is found at

40º which is 2.5712N. When height of the main pipe or


Fig.6(b) maximum tangential force is found at 30º



Fig.6(c) maximum tangential force is found at 40º



Fig.6(d) maximum tangential force is found at 40º


nozzle from the glass plate is 22.16cm as shown in Fig.6

(e) maximum tangential force is found at 40º which is

2.7208N. When height of the main pipe or nozzle from

a

e

c d

f

b

ba

d

e

c

f

ICMIEE18-326- 5

the glass plate is 24.7cm as shown in Fig.6(f) maximum

tangential force is found at 40º which is 2.2205N.


First fixed the height and angle of jet is manipulated to

find out different value of the forces. When height of

the main pipe or nozzle from the glass plate is 12 cm as

shown in Fig.7(a) maximum tangential force is found at

40º which is 3.3972N. When height of the main pipe or

nozzle from the glass plate is 14.54 cm as shown in

Fig.7(b) maximum tangential force is found at 30º



Fig.7(c) maximum tangential force is found at 30º



Fig.7(d) maximum tangential force is found at 30º

which is 3.2273N.


plate when h=12 cm (a); h=14.54cm (b); h=17.08 cm

(c); h=19.62 cm (d); h=22.16 cm (e); h=24.7 cm (f) and


In the experiment when velocity of jet is used

7.2236m/s maximum tangential force 2.5987N is found

at 30º relative angle and at a relative height of 24.7cm.

When the velocity of jet is used 10.01m/s the maximum

tangential force 2.8167N is found at 40º relative angle

and at a relative height of 19.62cm. When the velocity

of jet is used 13.676m/s the maximum tangential force

3.623N is found at 40º relative angle and at a relative

height of 17.08cm. Theoretically maximum tangential

force could have been found at 45º relative angle as sine

and cosec curve intersect at 45º each other at which

tangential force and normal force would be same.

Robinson et al. [14] showed that the higher shearing and

slicing force was obtained when the angle of water jet is

set from 0º-40º. In the experiment, the maximum

tangential force was found between 30º-40º relative

angle of jet. This is because of the splashing area which

was large in these regions along tangential direction.

But if further decreases the angle splash area increases

but striking force would be decreases enough and liquid

droplets increases which lowered the magnitude of

tangential velocity. From the Fig.8, a relation of

velocity, tangential force and height of the main pipe

corresponding to the glass plate is obtained. From the

Fig.8 it is seen that when velocity is increasing

tangential force is also increasing but the relative height

at which maximum tangential force was found is

decreasing. Because as height is increasing the length of

the impinging water jet from nozzle to the glass plate

also increasing, as a result the contact area of water and

ambient air is increasing. For these reason frictions

between air and water jet is increasing with increasing

the relative height of nozzle corresponding to glass plate.

As a result, striking force as well as tangential force of

impinging jet is decreasing with the increase of relative

height.

Fig. 8 Velocity vs. height and tangential force

If the velocity is increasing striking force as well as

tangential force of water jet is increasing. But the

angular position of impinging water jet at which

maximum tangential force is occurred, is found between

30º-40º.

a b

c d

fe

Tan

ge

nti

al

forc

e,

N

Heig

ht,

cm

Velocity, m/s

Height, cm

Tangential force, N

ICMIEE18-326- 6

Generally, low carbon tempered glass sheets are used as

the glazing material on the solar collector. The thickness

of these glasses are varies from 3-5mm. the tensile

strength of these sheets are varies from 40-50 N/mm2

and the pressure resistance varies from700-900 N/mm2

[15]. So, there is negligible damaging effect of using the

velocity described above.

In this study, one nozzle is used for finding out the

better position of that nozzle relative to the glazing

material. After choosing the better position several

nozzles should be used along the line of the glazing

material of flat plate solar collector for cleaning using

minimum amount of water.

5. Conclusion

This paper will focus mainly on the better cleaning

process of solar PV collector to reduce the losses

originated from dust. Dust is removed by the tangential

force originated from water jet impact through a nozzle

which is located at the optimum position corresponding

to the collector without creating any damage of the

collector. The paper investigated the optimum position

of nozzle with respect to glass at which dust removing

rate is maximum. After using jet of different velocity, it

is seen that maximum tangential force was found

between 30º to 40º relative angle of impacted jet with

respect to the glazing material at which maximum

cleaning can be possible. At this position maximum

possible dust would be removed so that maximum

possible solar beam can be reached to the receiver.

when velocity is increasing tangential force is also

increasing but the relative height at which maximum

tangential force was found is decreasing.

References

[1] A. Alshehri, Brian Parrott*, A. Outa, A. Amer,

F. Abdellatif, H. Trigui, P. Carrasco, S. Patel, I.

Taie, Dust mitigation in the desert: Cleaning

mechanisms for solar panels in arid regions,

2014 Saudi Arab. Smart Grid Conf. SASG 2014,

pp 1–6, (2014).

[2] M. Abd-Elhady, S. I. M Zayed, C. C. M. Rindt,

Removal of dust particles from the surface of

solar cells and solar collectors using surfactants,

Proc. Eurotherm …, vol. 2011, no. 2010, pp

342–348, (2010).

[3] R. A. Sims, A. S. Biris, J. D. Wilson, C. U.

Yurteri , M. K. Mazumder, C. I. Calle, C. R.

Buhler, Development of a transparent self-

cleaning dust shield for solar panels, Proc. ESA-

IEEE Jt. Meet. Electrost., no. 1, pp 814–821,

(2003).

[4] A. Fernández-García, L. Álvarez-Rodrigo, L.

Martínez-Arcos, R. Aguiar, J. M. Márquez-

Payés, Study of different cleaning methods for

solar reflectors used in CSP plants, Energy

Procedia, vol. 49, pp 80–89, (2013).

[5] G. He, C. Zhou, Z. Li, Review of self-cleaning

method for solar cell array, Procedia Eng., vol.

16, pp 640–645, (2011).

[6] K. A. Moharram, M. S. Abd-Elhady, H. A.

Kandil, H. El-Sherif, Influence of cleaning

using water and surfactants on the performance

of photovoltaic panels, Energy Convers. Manag.,

vol. 68, pp 266–272, (2013).

[7] A. K. Mondal, K. Bansal, A brief history and

future aspects in automatic cleaning systems for

solar photovoltaic panels, Adv. Robot., vol. 29,

no. 8, pp 515–524, (2015).

[8] M. K. Mazumder, M. Horenstein, J. Stark, D.

Erickson, A. Sayyah, S. Jung, F. Hao,

Development of Self-Cleaning Solar Collectors

for Minimizing Energy Yield Loss Caused by

Dust Deposition, Part. Sci. Technol., no.

November 2015, pp 1–10, (2014).

[9] Y. B. Park, H. Im, M. Im, Y. K. Choi, Self-

cleaning effect of highly water-repellent

microshell structures for solar cell applications,

J. Mater. Chem., vol. 21, no. 3, pp 633–636,

(2011).

[10] J. Y. Hee, L. V. Kumar, A. J. Danner, H. Yang,

C. S. Bhatia, The effect of dust on transmission

and self-cleaning property of solar panels,

Energy Procedia, vol. 15, no. December 2012,

pp 421–427, (2012).

[11] S. Ghazi, A. Sayigh, K. Ip, Dust effect on flat

surfaces - A review paper, Renew. Sustain.

Energy Rev., vol. 33, pp 742–751, (2014).

[12] J. K. Kaldellis, M. Kapsali, Simulating the dust

effect on the energy performance of

photovoltaic generators based on experimental

measurements, Energy, vol. 36, no. 8, pp 5154–

5161, (2011).

[13] S.Mekhilef, R. Saidur, M. Kamalisarvestani,

Effect of dust, humidity and air velocity on

efficiency of photovoltaic cells, Renew. Sustain.

Energy Rev., vol. 16, no. 5, pp 2920–2925,

(2012).

[14] D. S. Robinson, Experimental Investigation of

Effect of Abrasive Jet Nozzle Position and

Angle on Coating Removal Rate, International

Journal of Manufacturing Systems, 1: 57-64,

(2011).

[15] Flat Plate Solar Collector Glazing Materials--

Tempered Solar Glass, Qingdao Migo Glass Co.,

Ltd.

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I ICMIEE18-326CMIEE18-326 Cleaning of Accumulated Dust